Verapamil, a calcium channel blocking agent, has been shown to be an effective new therapeutic agent for the treatment of patients with hypertrophic cardiomyopathy. In order to determine whether other drugs of this type will be equally effective, nifedipine was compared with verapamil and placebo administration in a double-blind randomized study. Early results indicate that both verapamil and nifedipine can improve exercise capacity and symptomatic status in patients with hypertrophic cardiomyopathy, but patients must be carefully chosen because serious adverse drug effects can occur.